1. Field of the Invention
This invention relates to an electrical power carrying vacuum hose assembly, method of making same, and a vacuum cleaner employing such hose assembly.
2. Prior Art Statement
Canister type vacuum cleaners are widely used in industry and each of such vacuum cleaners normally employs a vacuum tank having an electric powered vacuum unit, an electric motor driven cleaning instrument for operation remotely from the vacuum tank, and a vacuum hose assembly operatively connecting the cleaning instrument to the tank wherein the vacuum hose assembly usually has a pair of wires extending therealong which serve the dual purpose of electrical conductors and hose reinforcing wires. These dual-purpose wires due to their reinforcing character have a comparatively high electrical resistance which tends to cause substantial heating thereof and of electrical leads of the vacuum cleaner electrical system which are operatively connected to such wires. However, it is possible to encounter abnormal electrical operating conditions due to so-called electrical short circuits, malfunction or stalling of an electric motor associated with the cleaning instrument, poor manufacturing controls, on electrical leads and other electrical system components, and the like.
It is also common practice for many canister type vacuum cleaners of this type to be provided with protective fuses which are actuated by comparatively high electrical current. However, these current actuated fuses have their own characteristic deficiencies including some which are slow acting or act after a designed time delay whereby it is possible to have a safety problem even in a canister type vacuum cleaner which is protected by a high electric current actuated fuse. Indeed, it is possible under abnormal electrical operating conditions of the character mentioned for the electrical conductors of the vacuum cleaner electrical system and particularly the dual-purpose wires comprising the hose assembly to become sufficiently hot to burn their electrical insulation and possibly start a larger fire as well as present the potential hazard of electrical shock due to fire-exposed leads.